The heart is the center of a person's circulatory system. The left portions of the heart, including the left atrium (LA) and left ventricle (LV), draw oxygenated blood from the lungs and pump it to the organs of the body to provide the organs with their metabolic needs for oxygen. The right portions of the heart, including the right atrium (RA) and right ventricle (RV), draw deoxygenated blood from the body organs and pump it to the lungs where the blood gets oxygenated. These mechanical pumping functions are accomplished by contractions of the heart. In a normal heart, the sinoatrial (SA) node, the heart's natural pacemaker, generates electrical impulses, called action potentials, that propagate through an electrical conduction system to various regions of the heart to cause the muscular tissues of these regions to depolarize and contract at a normal sinus rate.
Electrocardiography (ECG) is known to indicate the functions of the electrical conduction system by monitoring the action potentials at various portions of the heart. A QRS complex is a segment of an ECG signal that indicates depolarization of the ventricles. An abnormally wide QRS complex is an indication that the conduction of the electrical impulses through the ventricles is prolonged. The prolonged conduction may result from conditions related to heart failure, including hypertrophy or dilatation of one or both ventricles and/or blockage of the Purkinje fibers that conduct the electrical impulses in the ventricles. Thus, physicians and other caregivers use the width of the QRS complex as an indication of abnormal cardiac conditions, including heart failure, that may need medical treatments.
Implantable CRM devices such as pacemakers and defibrillators are used to treat cardiac arrhythmias, heart failure, and other cardiovascular disorders by delivering electrical energy to the heart. An abnormally wide QRS complex is one of the factors that prompt a physician or other caregiver to consider an application or adjustment of a cardiac electrical therapy using an implantable CRM device.
For these and other reasons, there is a need for an easy and convenient way to detect wide QRS complexes and, if detected, communicate the result to a physician or other caregiver for consideration of applying or adjusting the cardiac electrical therapy.